Influence of Fatigue in Swimmers Suffering from Swimmer Shoulder Pain

The shoulder joint is susceptible to be damaged in sports with overhead actions, often leading to swimmer shoulder pathology. Fatigue can also worsen and increase the risk of overuse injuries. Evaluating shoulder kinematics during swimming is crucial to identify injury-related movement patterns and to provide a correct physiotherapy treatment. To measure kinematics, inertial and magnetic measurement systems (IMMSs) offer a very versatile approach with respect to traditional video-based systems. This preliminary study focuses on the effects of fatigue on shoulder joint kinematics in swimmer with swimmer shoulder compared to healthy swimmers, by using IMMS. 11 young swimmers (5 pathological, 7 male) took part in the study. Each participant executed 40 s of dry front crawl followed by a fatiguing protocol and by other 40 s of dry front crawl. We analyze the arm movement relative to the thorax examining the differences of the movement amplitudes between healthy and pathological subjects and before and after fatigue exercise according to the three rotations: Flexion/Extension, Abduction/Adduction, and Internal/External rotation. Some slight non-significant differences were found after exercise compared to before in all the three rotations while a significant difference between healthy and pathological subjects was found in Flexion/Extension rotation both before and after fatigue exercise. The use of IMMS allowed to verify the repeatability of the kinematic movement and to quantify the rotation angles identifying which component of the movement is most affected by the swimmer shoulder pathology. However, a larger number of subjects is necessary in order to confirm the results.